Eye-Fi cards | Wireless connection for your camera

Eye-Fi cards are SD memory cards which contain a built-in wireless transmitter. Providing you’re within reach of a suitable wireless hotspot, you can then transmit your pictures to a photo sharing site or, if you’re at home and have a wireless router, you can send them to your computer.

Eye-Fi Explore cards can also ‘geotag’ your photos. This isn’t done directly within the camera, though – the location information is added to the photos later using software on your computer. Eye-Fi cards don’t contain a conventional GPS receiver. Instead, they look for nearby wireless hotspots and use a service called Skyhook to look up their location.

As a result, coverage is variable and probably not as reliable as conventional GPS right now. It’s quick and simple, though, and as the Wi-Fi card demonstrates, the technology can be fitted into a tiny space.

Eye-Fi cards are very clever, but make sure you camera is Eye-Fi compatible before you invest.

Wi-Fi | Or should that be 'Why-Fi'?

Broadly, 'wireless' means any cable-free connection. Wireless technology is used extensively in digital photography for controlling devices or transferring photos. Many cameras can be operated with optional 'wireless remotes', some can transmit pictures wirelessly to printers or even over the Internet to other computers, and some cameras use wireless flash systems.

'Wi-Fi' is used to mean a wireless network which you can use to transmit photos or communicate with other computers. Nearly all laptops and notebooks these days come with built in 'WiFi', or wireless networking, but it's not yet common on cameras.

Nikon's CoolPix S52c (now discontinued) was able to send pictures to Nikon's My Picture Town website where they could be forwarded as emails to other people. Samsung's ST1000 (pictured above) goes further, though, with the ability to email pictures directly.

Some professional D-SLRs have Wi-Fi add-ons that enable photographers to send pictures back to their clients without leaving their location - though most will use laptops which will be able to achieve the same thing much more easily.

The main limitation at the moment is that devices like these need an 'open' wireless hotspot which doesn't require any authentication. Most hotels, restaurants and other public buildings have 'closed' networks which only become available on payment of a fee, and then require an authentication process which is simple enough on a computer but more problematic on a device like a camera which lacks a keyboard.

PAL and NTSC | Less important with the arrival of HD

PAL and NTSC are the two most commonly-used broadcast formats around the world. PAL is used in the UK, NTSC in the US. Digital cameras and camcorders need to produce the right output for the TV they're connected to. The distinction between PAL and NTSC is likely to become less relevant, though, as digital and high-definition broadcasting take over from conventional analogue transmissions – PAL and NTSC are old fashioned 'standard def' technologies.

It's not just broadcast TV which will be affected. It look as if digital devices will increasingly connect to high-definition TVs via digital HDMI cables (below) rather than old-fashioned analogue PAL/NTSC connectors.

Digital cameras and high-definition camcorders now shoot in a variety of digital formats, but you will still need to select PAL or NTSC if you produce DVDs for playback on domestic TVs and DVD players. The movie editing/DVD software will then carry out the necessary conversions.

PAL and NTSC do use different frame rates (25fps and 30fps respectively). Movie editing software can adjust the frame rate when you export, so that if your device captures footage at 30fps (most do), the software can adjust this to 25fps on export using complex resampling techniques. The results won't be quite as good, however, as if you'd shot at 25fps in the first place.

This is reflected in the latest generation of digital SLRs with movie modes. Where compacts almost always shoot at 30fps, these SLRs typically shoot at 25fps (Panasonic GH1) or offer a choice between 25fps and 30fps (Canon EOS 7D).

HDMI | One size doesn't fit all

HDMI stands for High Definition Multimedia Interface, and it’s used for connecting high-definition devices like HDTVs and HD cameras and camcorders. HDMI connectors come in four sizes. The largest is Type A, there’s a Type B capable of higher data transfer speeds which may become significant in the future, and a smaller Type C (sometimes called HDMI mini) which is commonly used on cameras and camcorders. There’s also an even smaller Type D.

Annoyingly, high definition devices with an HDMI output seldom come with HDMI cables - these are optional (or do we mean compulsory?) extras. You need to make sure you get a cable with the right-sized connectors on either end.